Edible dock protein-phloretin nanoemulsion: Fabrication, characterization, and stabilization

Phloretin (Phl) is a promising bioactive polyphenol but severely limited in practical applications due to its intrinsically low water solubility and chemical instability. Edible dock protein (EDP), an emerging plant protein with superior hydrophobicity and emulsification capacity, can form stable nanoemulsion with phloretin via protein-polyphenol noncovalent interactions, serving as an effective delivery vehicle. In this research, the influence of EDP concentration on the physicochemical characteristics, interfacial properties, and stabilization efficacy of EDP-Phl nanoemulsion was systematically explored. The optimized nanoemulsion at 0.3% EDP exhibited uniform droplet size (115.8 nm), suitable zeta potential (-28.5 mV), and low polydispersity index (0.193), corresponding to the highest encapsulation efficiency (92.4%) and loading capacity (12.45%). Confocal laser scanning microscopy confirmed regular spherical oil-in-water nanostructures. Saturation interfacial adsorption of EDP was achieved at 0.3% protein content, generating a compact and stable interfacial film. Simulated gastrointestinal digestion revealed that phloretin retention exceeded 86%, and its antioxidant activity was remarkably enhanced via EDP-based nanoencapsulation. At 0.3% EDP, the protein molecule formed a dense interfacial layer. The hydrophobic groups faced the oil phase, and the hydrophilic groups faced the aqueous phase. This structure improved the interfacial stability. These findings elucidated the stabilization mechanism driven by protein-polyphenol interactions and supported the application of EDP nanoemulsion as food-grade delivery systems for hydrophobic bioactives.